Method of obtaining dry, uncontaminated seals on flexible pouches

ABSTRACT

A method of obtaining dry uncontaminated seals on flexible pouches. The longitudinal side seams of the pouch are sealed to within about three-quarters of an inch of the top thereof leaving a pair of free flaps. The latter are then folded rearwardly and downwardly through 880* against the front and rear panels of the pouch. The flaps are then immobilized in this position by opening the pouch which is then filled with a product. The flaps are then returned to an upright position such as by pulling the top of the pouch flat in a togglelike action and sealed preferably with a slight overlap of the original side seam seal.

United States Patent Hutcheson Mar. 7, 1972 [54] METHOD OF OBTAINING DRY, 3,077,709 2/1963 Kauffeld ..53/37 UNCONTAMINATED SEALS on 3,340,671 9/1967 Loo ..s3/39 x Primary Examiner-Travis S. McGehee Attorney-Glenn, Palmer, Lyne, Gibbs & Thompson [57] ABSTRACT A method of obtaining dry uncontaminated seals on flexible pouches. The longitudinal side seams of the pouch are sealed to within about three-quarters of an inch of the top thereof leaving a pair of free flaps. The latter are then folded rearwardly and downwardly through 880 against the front and rear panels of the pouch. The flaps are then immobilized in this position by opening the pouch which is then filled with a product. The flaps are then returned to an upright position such as by pulling the top of the pouch flat in a togglelike action and sealed preferably with a slight overlap of the original side seam seal.

2Claims, 7 Drawing Figures METHOD OF OBTAINING DRY, UNCONTAMINATED SEALS ON FLEXIBLE lPO UCIIES This invention relates to a method of sealing pouches and more particularly to a method of sealing flexible pouches so as to effect dry, uncontaminated top seal areas when the pouches are filled with a food product or the like.

Heretofore, difficulty has been experienced in filling and sealing flexible pouches with a food product in that the food product tends either to moisten or contaminate the top flaps or lips of the pouch which then prevents a hermetic seal from being formed. In some instance, such as where the product is stringy in nature as in the case of sauerkraut, the product extends entirely across the top flaps or lips thereby resulting in an unsatisfactory seal.

In accordance with the present invention, the top flaps are folded downwardly and rearwardly through 180 prior to the filling operation so as to lie against their respective front and rear panels. The pouch is then opened which results in a togglelike action for the top flaps whereby they are immobilized against the front and rear panels. After the pouch is filled, the flaps are returned to an upright position and the top seal may then be effected without fear of an unsatisfactory seal being formed caused by moistened or contaminated top flaps.

In accordance with the method of this invention, the pouch may be steam flushed to remove air from the pouch without forming condensation on the final seal surfaces. If the pouch is vacuum sealed, the vacuum tube used therefor will not pull out contaminants into the seal area. The method of the present invention is particularly well suited for continuous motion, high-output packaging machines.

The inherent advantages and improvements of the present invention will become more readily apparent upon considering the following detailed description of the invention and by reference to the drawings in which:

FIG. 1 is a perspective view diagrammatically illustrating a pouch in the process of its formation;

FIG. 2 is a perspective view of the pouch of FIG. 1 after it has been side seamed;

FIG. 3 is a perspective view of the pouch of FIG. 2 with the top flaps folded rearwardly and downwardly;

FIG. 4 is a perspective view of the pouch of FIG. 3 after it has been opened and filled with a product;

FIG. 5 is a perspective view of the pouch of FIG. 4 illustrating the return of the top flaps to their original position;

FIG. 6 is a perspective view illustrating the pouch of FIG. 5 following the top seaming thereof; and,

FIG. 7 is a fragmentary cross-sectional view of a typical pouch material taken along line 7-7 of FIG. 1.

While the method of the present invention is disclosed in connection with the formation of a single pouch, it is to be understood that the method of the present invention can be practiced continuously on a web of material from which individual pouches are formed.

Referring now to FIG. 1, there is illustrated a pouch-forming material indicated generally at 10 from which a pouch may be formed having a rear panel 12, a front panel 14 and a bottom fold line 15. It is to be understood that while the method of the present invention is illustrated in connection with a pouch having a folded bottom, the pouches may be formed two sheets or webs of material wherein the bottom is fin sealed instead of being folded as at 15.

FIG. 2 illustrates a subsequent operation in the formation of a pouch 10 wherein side seams l6 and 18 have been heat sealed to within about three-quarters of an inch from the top of the pouch. This sealing operation leaves a rear flap 20 and front flap 22. The side seam areas are typically formed by a heat-seal operation with the inner material on the pouch being made from a plastic or heat-scalable material.

In FIG. 3, the top flaps 20 and 22 have been folded rear- 5 wardly and downwardly through l80 so as to lie against the rear and front panels 12 and 14, respectively.

In order to ensure that the inner surfaces of rear flap 20 and front flap 22 are not moistened or otherwise contaminated by a product during filling of the pouch the opposed sides of the 10 pouch 10 are squeezed inwardly toward each other thereby opening the pouch for conventional filling with a product 24 as depicted in FIG. 4. This results in a buckling 0r togglelike action of the flaps 20 and 22 thereby immobilizing them against the front and rear main panels of the pouch so that the inner surfaces thereof are fixed during the filling operation away from the inside of the pouch so as not to be moistened and/or contaminated by product 24.

As illustrated in FIG. 5, the rear flap and front flap 22 are thereafter returned to their original positions preferably by 20 pulling the top of the pouch flat as indicated by directional arrows 26 and 28 to reverse the togglelike action and to flip the flaps 20 and 22 to their upright position.

FIG. 6 illustrates the formation of a top seam as is indicated generally at 30 wherein heat-sealable dies effect a seal which overlaps the top seam with the longitudinal side seams l6 and 18 in the areas indicated at 32 and 34, respectively.

A typical material for the pouch construction is shown in FIG. 7 wherein the exterior surface 36 is a barrier material such as aluminum foil and the interior material laminated 30 thereto at 38 is a heat-scalable plastic material. Where nonfood products are being packaged in the pouch 10, the heatsealable plastic material may be polyethylene or the like but where the product is a food product, it is preferable to use a heat-scalable plastic which will not impart a flavor to the food product. Examples of heat-sealable materials which may be employed are nylon and polypropylene.

It will be obvious that with the method of forming a pouch in accordance with the present invention it is possible to steam flush the pouch in order to remove air from the interior of the 40 pouch without effecting a condensation of the steam on the final seal surfaces. Similarly, it is possible to insert a tube into the interior of the pouch l0 and draw a vacuum therethrough without pulling the product upwardly in a manner to contaminate the final seal surfaces.

While presently preferred embodiments of the invention have been illustrated and described, it will be recognized that the invention may be otherwise variously embodied and practiced within the scope of the claims which follow.

What is claimed is:

1. A method of sealing flexible pouches comprising the steps of a. sealing the longitudinal side seams of a pouch leaving a pair of upstanding flaps,

b. reversely folding said flaps rearwardly and downwardly through 180,

c. opening said pouch to immobilize said flaps,

d. filling said pouch,

e. returning said flaps to an upright position by pulling on opposite edges to effect a reverse togglelike action in bringing said flaps to their upright position,

f. and completing the seal of said pouch by sealing said flaps together and by effecting an overlap seal with the previously sealed longitudinal side seams of said pouch.

2. A method of sealing flexible pouches as defined in claim 5 I wherein the side seams of said pouch are originally sealed to within three-quarters of an inch from the top of said pouch. 

1. A method of sealing flexible pouches comprising the steps of a. sealing the longitudinal side seams of a pouch leaving a pair of upstanding flaps, b. reversely folding said flaps rearwardly and downwardly through 180*, c. opening said pouch to immobilize said flaps, d. filling said pouch, e. returning said flaps to an upright position by pulling on opposite edges to effect a reverse togglelike action in bringing said flaps to their upright position, f. and completing the seal of said pouch by sealing said flaps together and by effecting an overlap seal with the previously sealed longitudinal side seams of said pouch.
 2. A method of sealing flexible pouches as defined in claim 1 wherein the side seams of said pouch are originally sealed to within three-quarters of an inch from the top of said pouch. 